1. Field of the Invention
In some embodiments this invention relates to a polishing composition and a rinse composition, and more specifically to a polishing composition and a rinse composition that are used in the treatment of silicon wafers to reduce the haze level of the surfaces of those silicon wafers.
2. Description of the Related Art
Highly integrated and high-speed ULSIs are manufactured in accordance to a fine-design rule. In order to satisfy the design rule, the focal depth of recent aligners is becoming shallower, and a flawless flat surface is required for silicon wafers for forming semiconductor devices. Haze level and light point defect (LPD) are used as indices representing surface characteristics (the degree of flaws and flatness).
Haze means milky-white clouding seen on the surface of a mirror-finished silicon wafer, and a haze level indicates the degree of the milky-white clouding. The clouding is caused by the diffused reflection of strong light radiated onto the silicon wafer, and can be visually observed.
LPD is the defect on the surface of a silicon wafer, and is caused by foreign substances adhered on the surface (hereafter also referred to as particles).
A polishing composition according to the first conventional method contains silicon dioxide, water, a water-soluble polymer (such as hydroxyethyl cellulose), a basic compound (such as ammonia), and a compound having 1 to 10 alcoholic hydroxyl groups (such as methanol).
Japanese Patent Laid-Open Publication No. 11-116942 discloses a polishing composition according to the second conventional method containing silicon dioxide, water, a water-soluble polymer, and a nitrogen-containing basic compound having 1 to 10 alcoholic hydroxyl groups (such as monoethanolamine).
By the action of the above-described water-soluble polymer, alcoholic compound, or nitrogen-containing basic compound, the quantity of particles adhered on the wafer surface are decreased, and the LPD is improved.
However, the polishing compositions according to the first and second conventional methods could not satisfactorily reduce the haze level on the surface. Therefore, there has been a demand for a treating method and a composition that can provide silicon wafers having surfaces of a reduced haze level.